PAROXETINE TABLETS AND PROCESS TO PREPARE THEM

Abstract: Paroxetine which is formulated into tablets using a formulation process in which water is absent.

Description: Paroxeti ne tabl ets and process to prepare them The present invention relates to novel formulations and to the use of the formulation in the treatment and/or prevention of certain disorders. US Patent 4,007,196 describes certain compounds which possess anti- depressant activity. One specific compound mentioned in this patent is known as paroxetine and which has the following formula: This compound has been approved for human use and is being sold in many countries around the world as an anti-depressant agent. It has been noticed that tablets of paroxetine often develop a pink hue which is highly undesirable. To date, all tablets which have been sold have been formulated using an aqueous granulation process. It has surprisingly been found that formulation of paroxetine into tablets can be carried out reliably and on a commercial scale using a formulation process in which water is absent, such as by direct compression or by dry granulation. It has also been surprisingly found that paroxetine formulated into a tablet using a process in which water is absent, is much less likely to develop a pink hue. Accordingly, the present invention provides paroxetine which is formulated into tablets using a formulation process in which water is absent. Examples of such a formulation process are dry direct compression of paroxetine or dry granulation of paroxetine followed by compression into tablets. The present invention therefore provides a formulation comprising direct compressed paroxetine admixed with dry excipients in the form of a tablet and a formulation comprising dry granulated and compressed paroxetine admixed with dry excipients in the form of a tablet. It should be appreciated that the term "dry" means substantially "dry" as opposed to the wholesale addition of water which was previously employed in the wet granulation process. Direct compression techniques are generally known in the art of pharmaceutical science. For example, paroxetine is conventionally admixed with dry excipients and compressed into tablets. Dry granulation techniques are generally also known in the art of pharmaceutical science. For example, paroxetine is conventionally admixed with dry excipients and compressed into large slugs or roller compacted into ribbon-like strands. The compacted material is then suitably milled to produce a free flowing powder which is then compressed into tablets. Additional excipients may then be added and mixed with the free flowing powder before being compressed into tablets. Examples of excipients include calcium phosphate, microcrystalline cellulose, sodium starch glycollate and magnesium stearate which may be admixed in appropriate ratios. It should be appreciated that particularly good results are obtained when microcrystalline cellulose is absent from the formulation, this is surprising as tablets formulated in the absence of microcystalline cellulose are often prone to breaking up during manufacture or storage. The par oxetine/excipient mixture may be compressed into an appropriate tablet shape. Preferred shapes include a pentagonal circumcircle, oval, round bi- convex or a tilt-tablet such as those described in US Patent 4,493,822. Paroxetine when incorporated into the above-mentioned tablets is suitably, present as the hydrochloride hemi-hydrate form which may be prepared according to the procedures outlined in US Patent 4,721,723. The amount of paroxetine present in the above-mentioned tablets is in the range of 10 to 100 mg of paroxetine as measured in terms of the "free base". Particularly preferred amounts include 10 mg, 20 mg, 30 mg, 40 mg and 50 mg of paroxetine as measured in terms of the "free base". Particularly preferred amounts include 20 mg, 30 mg and 40 mg of paroxetine as measured in terms of the "free base". Suitable procedures for preparing paroxetine include those mentioned in US Patents 4,009,196, 4,902,801, 4,861,893 and 5,039,803 and PCT/GB 93/00721. It has been mentioned that paroxetine has particular utility in the treatment of depression, paroxetine may also be used in the treatment of mixed anxiety and depression, obsessive compulsive disorders, panic, pain, obesity, senile dementia, migraine, bulimia, anorexia, social phobia and the depression arising from pre¬ menstrual tension and adolescence. The present invention therefore also provides a method of treating or preventing any of the above disorders which comprises administering an effective or prophylatic amount to a sufferer in need thereof of paroxetine which is formulated into a tablet using a process in which water is absent. The present invention further provides a pharmaceutical composition comprising paroxetine which is formulated into a tablet using a process in which water is absent for use in treating or preventing of the above disorders. The present invention further provides the use of paroxetine which is formulated into a tablet using a process in which water is absent in the manufacture of a medicament for treating or preventing the above disorders. The following examples illustrate the present invention: Example 1 INGREDIENTS 20 mg Tablet 30mg Tablet Paroxetine hydrochloride 22.67 mg 34.0 mg hemihydrate Dicalcium Phosphate (DCP) 83.34 mg 125.0 mg Microcrystalline Cellulose 50.67 mg 76.0 mg Sodium Starch Glycollate 8.34 mg 12.5 mg Magnesium Stearate 1.67 mg 2.5 mg Tablet Weight 166.7 mg 250.0 mg Commercial source of the ingredients Dicalcium Phosphate Dihydrate Emcompress or Ditab* Microcrystalline Cellulose Avicel PH 102* . . Sodium Starch Glycollate Explotab.* * Tradenames Method 1. Pass DCP through a screen and weigh it into a Planetary mixer. 2. Add 30 mesh Paroxetine to the bowl. 3. Add 20 mesh Avicel and Explotab and mix all the powders for 10 minutes. 4. Add magnesium Stearate and mix for 5 minutes. Tablet into Pentagonal Tablets using the following punches: 30 mg Tablet 9.5 mm Circumcircle 20 mg Tablet 8.25 mm Circumcircle The tablets are made satisfactorily on a single punch or a Rotary press. Example 2 INGREDIENTS 10 mg Tablet 20 mg Tablet 30mg Tablet Paroxetine hydrochloride hemihydrate 11.40 mg 22.80 mg , 34.20 mg Sodium Starch Glycollate 2.98 mg 5.95 mg 8.93 mg Granular Dicalcium Phosphate 158.88 mg 317.75 mg 476.63 mg (DITAB) or Dicafos Magnesium Stearate 1.75 mg 3.50 mg 5.25 mg Tablet Weight 175.00 mg 350.00 mg 525.00 mg Method Paroxetine, Sodium Starch Glycollate and Dicalcium Phosphate Dihydrate are screened and mixed together in a suitable mixer. (Planetary, Cuble or High Energy Shear mixer.) Add Magnesium Stearate and compress it into a tablet using a single punch or Rotary Tablet machine.

Claims: Claims 1. Paroxetine which is formulated into tablets using a formulation process in which water is absent. 2. A formulation process according to claim 1 which is a dry direct compression of paroxetine followed by compression into tablets or a dry granulation of paroxetine followed by compression into tablets. 3. A formulation process according to claim 1 or 2 in which paroxetine is admixed with dry excipients. 4. A formulation process according to claim 3 in which the paroxetine admixed with dry excipients is compressed into large slugs or roller compacted into ribbon-like strands. 5. A formulation process according to claim 4 in which the compressed or compacted material is milled to produce a free flowing powder and compressed into tablets. - 6. A formulation process according to claim 3, 4 or 5 in which the excipients are selected from calcium phosphate, microcrystalline cellulose, sodium starch glycollate and magnesium stearate which may be admixed in appropriate ratios. 7. A formulation process according to claim 3, 4, or 5 in which microcrystalline cellulose is absent from the formulation. 8. A formulation process according to claim 5 in which the tablet is compressed into a pentagonal circumcircle, oval, round bi-convex, or tilt-tablet shape. A formulation process according to any one of claims 1 to 8 in which paroxetine is in the form of the hydrochloride hemi-hydrate. 10. A formulation comprising direct compressed paroxetine admixed with any excipients in the form of a tablet. 11. A formulation comprising dry granulated and compressed paroxetine admixed with excipients in the form of a tablet. 12. A formulation according to claim 10 or 11 in which the excipients are selected from calcium phosphate, microcrystalline cellulose, sodium starch glycollate and magnesium stearate which may be admixed in appropriate ratios. 13. A formulation according to claim 10 or 11 in which the microcrystalline cellulose is absent. 14. A formulation according to any one of claims 10 to 13 in which the tablet is compressed into a pentagonal circumcircle, oral, round bi-convex or tilt-tablet shape. 15. A formulation according to any one of claims 10 to 14 in which the paroxetine is in the form of the hydrochloride hemi-hydrate.

Inventors: DOUGHTY DAVID GEORGE, PATHAK RAM DUTTA, DOUGHTY, DAVID, GEORGE, PATHAK, RAM, DUTTA
Applicants: DOUGHTY DAVID GEORGE, PATHAK RAM DUTTA, SMITHKLINE BEECHAM PLC, DOUGHTY, DAVID, GEORGE, PATHAK, RAM, DUTTA
Application year: 1994
Main classification: A61K31
IPC codes: A61K9, A61K31, A61P25